Most commonly, finings are substances added to wort or beer for the purpose of clearing or clarifying a beer. Some examples of beer clarification finings are whirlfloc, isinglass, Irish moss, bentonite, gelatin, kieselsol, chitosan and carrageenan. Most finings work as a binding agent, clumping together with residual proteins, solids, yeast, and tannins and sinking to the bottom of the kettle, fermenter, or holding vessel so that they can be excluded from the finished beer. In some cases the finings can also be used to enhance flavor or aroma by reducing sometimes undesirable particulates like tannins.
Below is a fining known as whirlfloc. A tablet is typically added 15 minutes prior to the end of a boil for a 5-10 gallon batch. Whirlfloc is a blend of Irish moss and carrageenan; when mixed with the boiling wort, it binds with proteins and beta-glucans, encouraging precipitation.